1. Field of Invention
The present invention relates to a method and an apparatus for driving a liquid crystal display (LCD), and more particularly to a method and an apparatus for driving an LCD by using different over-driving look-up tables (LUTs) to determine different display positions.
2. Related Art
In a stereoscopic viewing method of a display apparatus, different contents are displayed to the left eye and the right eye of a person. In particular, the stereoscopic viewing method requires for presenting different images to the left eye and the right eye of the person. In a special stereoscopic viewing method, that is, a time-sequential stereoscopic viewing method, images for the left eye and the right eye are presented alternately.
In order to ensure full stereoscopic viewing, alternating shutter glasses are typically used. After wearing the alternating shutter glasses, a user is enabled to view images on the left with his/her left eye at appropriate time, and view images on the right with his/her right eye at appropriate time.
FIG. 1 is a timing diagram of a conventional alternating shutter glasses in use. When a display apparatus collocating with the alternating shutter glasses is an LCD, a frame rate of the display apparatus must be increased from conventional 60 Hz to 120 Hz, and a vertical blanking interval VBI must be increased. Right-eye frame data R is written to a right-eye portion RE of the alternating shutter glasses S, left-eye frame data L is written to a left-eye portion LE of the alternating shutter glasses S, and the left-eye portion LE is turned on during a vertical blanking interval VBI. The operations are sequentially performed, such that images are transmitted to the brain through the human eyes (left and right eyes), and then combined into a stereoscopic image.
FIG. 2 is a graph showing a relation between a driving voltage and a gray level brightness and a display position in a conventional over-driving method. FIG. 3A is a graphical diagram of a picture presented on a display panel of an LCD. FIG. 3B is a corresponding timing diagram illustrating the timing for writing data to the left eye and the right eye. In a common conventional over-driving method used to accelerate the liquid crystal reaction, for upper data P1 of a display panel P of an LCD, reaction time RT1 taken for respectively writing current frame data F(n) and next frame data F(n+1) to the left-eye portion and the right-eye portion of the alternating shutter glasses S (see FIG. 1) is long (see FIG. 3B), thus resulting in over-shooting, in which the driving voltage is D, and the gray level brightness (curve) is G1. For lower data P3 of the panel, reaction time RT2 taken for respectively writing the current frame data F(n) and the next frame data F(n+1) to the left-eye portion and the right-eye portion of the alternating shutter glasses S (see FIG. 1) is short (see FIG. 3B), thus resulting in under-shooting, in which the driving voltage is also D, and the gray level brightness (curve) is G3. For middle data P2 of the panel, a normal liquid crystal reaction takes place, in which the driving voltage is also D, and the gray level brightness (curve) is G2. When the left-eye portion (or the right-eye portion) of the alternating shutter glasses S is turned on, the driving voltage is D, and G1>G3>G2 (see FIG. 2). Due to the difference between the gray level brightness G1, G2, and G3, poor image quality occurs, that is, ghosting and blurring occur when the display panel P undergoes an optical reaction (see FIG. 3A).